Organic light emitting diodes (OLEDs) have features of simple structure, ultra-thinness, and low power consumption. At present, OLED display devices have become a very promising flat panel display technology, and have been well appreciated by display device manufacturers. A variety of display devices using OLED panels have appeared in the market currently. From smart phones having OLED screens of wide color gamut and high resolution to large-sized OLED televisions of high contrast and large viewing angle, display devices adopting OLED panels show better performance than display devices adopting liquid crystal panels.
Compared to application of OLEDs in panel display, application of OLEDs in lighting field is still at an early stage of development. At present, in the market, OLED lighting lamps are of high prices and limited styles, and are basically single-sided lighting devices.
Double-sided OLED lighting lambs are in developing. US patent US 2007/0126354A1 discloses a double-sided OLED device. In the OLED device, OLEDs are prepared on two transparent substrates, respectively, and then the two substrates are encapsulated separately and fitted together to achieve double-sided light emission. However, this solution requires two substrates and requires that each of the substrates be encapsulated, thus leading to high cost and complexity of the whole structure. Chinese patent CN 101952967A provides a different solution, in which two OLED light-emitting layers are prepared on one substrate, and a third electrode is prepared between the two OLED light-emitting layers to achieve separate control over the two OLED light-emitting layers and double-sided light emission. However, this solution requires a third electrode, which also results in a complicated structure in a display panel. Besides, to achieve double-sided white light, there is a relatively high requirement for structures of OLEDs.
Therefore, it is desirable to provide an improved double-sided OLED so as to achieve a double-sided white OLED lighting panel having a simple structure.